Variable resistor for arc welder fields



Jan. 12, 1943. c. FJMULLENBACH 2,308,199

VARIABLE RESISTOR FOR ARC WELDER FIELDS Filed Jan. 6, 1942 2Sheets-Sheet l 4 INVENTOR.

0/424 Es/TMULLENBAcH I fiwwmmw Jan- 1943. c. F. MULLENBACH 0 VARIABLERESISTOR FOR ARC WELDER FIELDS Filed Jan. 6, 1942 2 Sheets-Sheet 2.\Tww\fi@ v CHARLES imam/V546 By W Hm A'rrom/zys.

objection to manipulating process of welding Patented Jan. 12, 1943 7Hunchback Application January 6, 1942, Serial No. 425,159-

2 Claims. (Cl. 201-48) I This invention relates to a variable resistorior arc welder fields. The conventional arc" weldingapparatus includes'.a power driven, direct current generator irom which conductors lead toan electrode holder and to the work that is to be welded. Ordinarily,the field winding oi the generator includes a variable resistancewhereby the field current can be controlled to vary the output currentsupplied to the electrode and the work. Such variable resistance-isnormally controlled itseli. In arc welding however it is irequentlydesirable to vary the output current supplied :by the generator whilethe welding is in progress. For example, in welding mitered joints oipipe usually less current is supplied in welding around amount oicurrent -supplied lute control of the welder at all times.

welding operation. In this way, the is under the abso stopping theWiththe ioregoing'and other objects in view, which will be made manifestin the following detailed description and specifically pointed out inthe appended claims, reierence is had to the accomp n drawings ior anillustrative embodiment' oi the invention, wherein:

Figure 1 is a perspective view illustrating an arc welding apparatusillustrating the invention -by a suitable handle mounted on thegenerator the convex side oi the joint than when welding around theconcave side oi the joint.. In certain types oi work it'is desirable tocause more current to be supplied than in other types. Also, whenwelding, it is desirable to out down the amount oi current supplied bythe generator at the end oi the head so as to eiiectively snuii out thearc.. Ordinarily. ii the arc is broken at the end of the bead a smallcrater is iormed in the weld. tending to weaken the weld at this ointwhich oi course is objectionable.- when the are is snuiied out bycutting down the field current 01' the generator, such objectionablecrater is avoided. When the resistance in the field winding iscontrolled by a handle on the generator it is diificult, ii at allpossible, to vary the current during the process oi welding as thewelder ordinarily .under these circumstances must break the arc, lay hiselectrode holder on a suitable support, and leave the work to adjust thehandie on the generator. Heretoiore attempts have been made toautomatically control the amount oi output current supplied by thegenerator or to vary the field winding resistance by manipulating a partoi the electrode holder. The automatic constructions do not enable theincrease or decrease oi current supplied to the weld when desired andthe a part oi the electrode holder is that it'is dimcult to hold theelectrode steady and continue with the welding while the fieldresistance is being adjusted.

- .An object oi the present invention is to provide a variable resistorfor are welder fields which is operable by the ioot oi the welder sothat the welder can increase or decrease the output cutrent iron thegenerator as desired during the without. breaking the are or as having.been incorporated therein or applied thereto; I

Fig. 2 Ba top plan view oi the resistor embodying the present invention,parts being broken away to illustrate the upper side oi theresistancewinding;

1'18. 3 is a upon the line 3-! indicated;

Fig, 4 is a horizontal section taken substantially upon the line 4-4upon Fig. 3 in the direction indicated:

Fig. 5 is a top plan view oi an alternative iorm oi variable resistorthat may be employed; and

Fig. 6 is a sectional view taken substantially upontheline Muslim-Fig.5.

Referring to the accompanying drawings wherein similar reierencecharacters designate similar parts throughout, in Fig. 1 there isillustrated an arc welding generator ll suitably power driven whichsupplies its output current to an electrode holder ii carryi a anelectrode l2 and the work It. The field winding oi the generator isconnected by electrical conductors within a cord it to a variableresistor II. The length oi the cord is is normally approximately equalto the length oi the conductors leading from the generator to theelectrode holder so that the variable resistor it can be positioned inthe neighborhood oi the location oi the work Ii that is to be welded.

The resistor illustrated in Figs. 2 to 4, inclusive, comprises asuitable housing I. having legs i! at its corners by which it issupported. This housing has a rock shait I! extended verticallysectional view taken substantially uporr Fig. 2 in the directioninsulating material 2| on which y the left as the case may forded by theresistance wire 2i thus down the amount of current supplied to theelecportable can be readily with the welding operation.

there are binding posts 22 which extend through ed as indicated at 24around the binding posts so that the contacts tap the resistance windingat various points.

on the bottom of the rock shaft I8 there is secured an insulating arm 25which in turn carries a spring actuated brush 26 arranged to wipe acrossthe cont: is 23. The conductors 21 and 28 within the cord I 4 come fromand lead back to the field winding of the generator. One of theseconductors leads to the brush 28 while the other conductor leads to theendmost contact 23. On the top of the housing there may be formedsuitable'indicia 29 indicating the extreme positions of the pedal l9when all of the resistance is either cut in or out in the generatorfield circuit.

In the preferred form 01' construction a suitable stop lug 30 is alsoformed on the top of the housing engageable by portions 3| on the underside of the pedal to limit rotational movement of the pedal.

The operation and advantages of this form of construction are asfollows: In welding the work i3 the welder may position one foot on thepedal i9 and proceed continuously with the welding giving his undividedattention thereto. If, in the course of the welding, it is desirable toincreaseor decrease the amount of output current from the generator thewelder accomplishes this by merely turning the pedal N to the right orto v be, to cut in or out out resistance in the-field. In this way thewelder may carefully maintain his are at all times, varying the amountof current supplied thereto as circumstances may require. 'At the end ofthe weld if he desires to avoid the objectionable crater occasioned bybreaking the arm the welder may cut in all of the available resistanceafcutting trode and in efiect snumng out the are as distinguished frombreaking it.

Ordinarily the resistor being small and readily carried to a locationsufliciently close to the work to enable the welder to operate the sameby his foot while proceeding In Figs. and 6, a slightly modified form ofconstruction is disclosed. Therein. the resistor tied at as havingcontacts 4a adapted to b traversedby the brush 4|. The brush which ismounted on the insulating arm 42 rotates on the bottom ofithe verticalshaft 43 as a center.

The am however has a slot or recess 44 cut therein through which extendsan arm 45 extending downwardly from the pedal 45. The pedal 56 rotatesone. horizontal shaft or pintle 41.

In this form of construction the operation andadvantagesof the variableresistor are the same as those previously explained. However, in thisform of construction instead of moving the pedal in a lateral directionor from right to left the pedal moves about a horizontal axis asindicated by the dotted and full-line positions shown in Fig. 6.Depressing the toe of the pedal causes the arm 42 to swing into thedotted line position illustrated in Fig. 5, and by relieving thepressure on the toe-of the pedal the arm 42 may be swung toward theopposite side of the resistance by means of a coil tension spring 48.

From the above described construction it will be appreciated that theimproved variable resistor is highly advantageous in that it enables thewelder to control the amountof current supplied to the arm at all times.This may be varied by the welder during the course of the weldingoperation in accordance with his desires or as circumstances mayrequire. By having the control located in the neighborhood of the weldit is unnecessary for the welder to discontinue the weldingoperation'while making an adjustment of the field resistance on thegenerator itself. Nor is it necessary for .him to manipulate theelectrode holder other than that necessarily involved in the course ofwelding. In other words, control ofthe resistance while it isaccomplished by the welder in the course of his welding he isnevertheless independent of the welding apparatus or electrode holderitself.

Various changes may be made in the details of construction withoutdeparting from the spirit or scope of the invention as defined by theappended claims.

I claim:

1. In combination with the generator of arc welding equipment, avariable resistance controlling the field oi the generator remote fromthe generator and operable by the foot of the welder.

2. In combination with the generator of arc welding equipment, avariable resistance connected to and controlling the field of thegenorator so as to vary the field current; and means operable by a limbof the welder independently 5 of his hands that may be holding anelectrode holder for adjusting the resistance.

1 7 CHARLES F. MUILENBACH.

